Undo/Redo Logging (cont)
Simplified view of recovery using UNDO/REDO logging:
- scan log to determine committed/uncommitted txs
- for each uncommitted tx
T add <ABORT T> to log
- scan backwards through log
- if
<T,X,v,w> and T is not committed, set X to v on disk
- scan forwards through log
- if
<T,X,v,w> and T is committed, set X to w on disk
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